Re: Slightly OT. Heat and a Bench Light ...

On Mon, 07 Jul 2008 10:31:08 -0700, Jeff Liebermann <jeffl@[EMAIL PROTECTED]
>
wrote:

>On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily"
><arfa.daily@[EMAIL PROTECTED]
> wrote:
>
>>The things I do for science !!
>

>
>Surface area of a sphere is 4Pi*r^2
>  Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm
>  New = 4 * 3.14 * 2.5^2 =  78.5 sq cm
>The new bulb has about 70% of the surface area as the old bulb.
>However, I gotta dust off the college thermodyamics texts before I can
>figure out the expected temperature rise given identical power
>dissipations.  I also gotta lookup the IR transmissivity of glass. The
>things I do for science...

The other unknown factor is the lamp efficiency.   So how much is
going out as light, and how much as heat.    A small change in this
ratio will certainly have an effect on the heating effect even with
identical sized globes.

Peter